when I have taken in untouch kennel dogs from breeding operations,, they are wild and unfocused. I put them in a safe place kennel, feed water shelter, and work on a simple daily routine depending on their level. if they untouchable I establish just the kennel area is where their food water and shelter is and be care giver to them not attempting any contact with them. Once they have a sense of security of their kennel I can start letting them into the larger fenced area attached to the kennel and they will return to the kennel.
These dogs are not street dogs, many of them are from well bred dogs that have had no learning.. When they settle in and start relaxing feel safe they fall back into the traits of their breed characteristics. GSD's are aloof but they are also naturally family orientated breed and team players. Main thing for them is trust and safety first then they seek out to interact but interaction does come from the breed.
As stated by 3GSD4IPO It may never evolve past what it is. Dogs raised for food are not raised for temperament and temperament is mostly genetic.
Don't want you to feel you personally have failed if it never evolves further for you.. do the best that you can... and send good thoughts your way